Not only can you use the pre-built labels, but you can also enhance them by
adding and removing sites from them. For example, if you find that some of
the pages that Google has labeled shopping_comparisons are not shopping-comparison pages or that Google has missed some great shopping comparison
sites, you can add or remove those sites. You can improve the shopping_comparisons label by adding the appropriate annotations in your search engine or in a collaborative search engine to which you have access.

Testing Search Labels

If you are not sure how a search label might work, you can experiment with it by using the more: search operator in a custom search engine. Take the search label called forum, for instance. Search for cartoon on Google search. Open a new browser window and this time, type more:forum cartoon in a custom search engine. Compare the search results between the normal search query and the search query appended with the more: operator and a search label.

Note: Do not include a space between the more: operator and the search label.

Creative Commons

You can have your search engine include only sites that have stated their Creative Commons license. Creative Commons copyright license indicates the rights that the creator wants to reserve and the rights they are willing to give away for the benefit of the community. Each label corresponds to a specific licensing term.

Note: You can use these labels with filter mode only. You cannot use them as boost or eliminate labels.

Images

Miscellaneous

News and Publication

Recency

You can use the recency labels to promote results by the freshness of the webpages. The labels vary in how intensely they boosts new content.

The weakest label, recent1, is best applied to search engines that search static content that is rarely updated, such as classic literature or archived reports. At the other extreme, recent4 is best applied to search engines that search current content that is frequently updated, such as daily stock or market reports. It is the closest approximation to "sorting by date." The other two labels are somewhere in between.

recent1

(static content that is updated rarely, such as annual reports, or archived documents)

recent2

(content that is updated approximately quarterly, such as reviews for bicycles)

recent3

(content that is updated approximately weekly or monthly, such as a magazine)

recent4

(current content that is updated daily, such as the news or comic strips)